/* canvas-toBlob.js
 * A canvas.toBlob() implementation.
 * 2016-05-26
 *
 * By Eli Grey, http://eligrey.com and Devin Samarin, https://github.com/eboyjr
 * License: MIT
 *   See https://github.com/eligrey/canvas-toBlob.js/blob/master/LICENSE.md
 */

/*global self */
/*jslint bitwise: true, regexp: true, confusion: true, es5: true, vars: true, white: true,
 plusplus: true */

/*! @source http://purl.eligrey.com/github/canvas-toBlob.js/blob/master/canvas-toBlob.js */

(function(view) {
	"use strict";
	var
		Uint8Array = view.Uint8Array
		, HTMLCanvasElement = view.HTMLCanvasElement
		, canvas_proto = HTMLCanvasElement && HTMLCanvasElement.prototype
		, is_base64_regex = /\s*;\s*base64\s*(?:;|$)/i
		, to_data_url = "toDataURL"
		, base64_ranks
		, decode_base64 = function(base64) {
			var
				len = base64.length
				, buffer = new Uint8Array(len / 4 * 3 | 0)
				, i = 0
				, outptr = 0
				, last = [0, 0]
				, state = 0
				, save = 0
				, rank
				, code
				, undef
				;
			while (len--) {
				code = base64.charCodeAt(i++);
				rank = base64_ranks[code-43];
				if (rank !== 255 && rank !== undef) {
					last[1] = last[0];
					last[0] = code;
					save = (save << 6) | rank;
					state++;
					if (state === 4) {
						buffer[outptr++] = save >>> 16;
						if (last[1] !== 61 /* padding character */) {
							buffer[outptr++] = save >>> 8;
						}
						if (last[0] !== 61 /* padding character */) {
							buffer[outptr++] = save;
						}
						state = 0;
					}
				}
			}
			// 2/3 chance there's going to be some null bytes at the end, but that
			// doesn't really matter with most image formats.
			// If it somehow matters for you, truncate the buffer up outptr.
			return buffer;
		}
		;
	if (Uint8Array) {
		base64_ranks = new Uint8Array([
			62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1
			, -1, -1,  0, -1, -1, -1,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9
			, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25
			, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35
			, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51
		]);
	}
	if (HTMLCanvasElement && (!canvas_proto.toBlob || !canvas_proto.toBlobHD)) {
		if (!canvas_proto.toBlob)
			canvas_proto.toBlob = function(callback, type /*, ...args*/) {
				if (!type) {
					type = "image/png";
				} if (this.mozGetAsFile) {
					callback(this.mozGetAsFile("canvas", type));
					return;
				} if (this.msToBlob && /^\s*image\/png\s*(?:$|;)/i.test(type)) {
					callback(this.msToBlob());
					return;
				}

				var
					args = Array.prototype.slice.call(arguments, 1)
					, dataURI = this[to_data_url].apply(this, args)
					, header_end = dataURI.indexOf(",")
					, data = dataURI.substring(header_end + 1)
					, is_base64 = is_base64_regex.test(dataURI.substring(0, header_end))
					, blob
					;
				if (Blob.fake) {
					// no reason to decode a data: URI that's just going to become a data URI again
					blob = new Blob
					if (is_base64) {
						blob.encoding = "base64";
					} else {
						blob.encoding = "URI";
					}
					blob.data = data;
					blob.size = data.length;
				} else if (Uint8Array) {
					if (is_base64) {
						blob = new Blob([decode_base64(data)], {type: type});
					} else {
						blob = new Blob([decodeURIComponent(data)], {type: type});
					}
				}
				callback(blob);
			};

		if (!canvas_proto.toBlobHD && canvas_proto.toDataURLHD) {
			canvas_proto.toBlobHD = function() {
				to_data_url = "toDataURLHD";
				var blob = this.toBlob();
				to_data_url = "toDataURL";
				return blob;
			}
		} else {
			canvas_proto.toBlobHD = canvas_proto.toBlob;
		}
	}
}(typeof self !== "undefined" && self || typeof window !== "undefined" && window || this.content || this));